Synthesis, Crystal Structure and Cytotoxicity Evaluation of 2-Phenoxy-4H-spiro{naphtho[2,3-e][1,4,2] oxazaphosphinane-5,10-dione,1 ′-cyclohexane} 2-Oxide

2-Phenoxy-4H-spiro { naphtho2,3-e] 1 ,4,2]oxazaphosphinane-5,10-dione, 1 ′-cyclohexane}2-oxide (C22H20NO5P) was synthesized by the Mannich-type reaction of 2-amino-3-hydroxy-1,4-naphthoquinone with phenyl phosphorodichloridite and cyclohexanone, and structurally characterized by single-crystal X-ray diffraction analysis. It crystallizes in monoclinic, space group P21/n with a = 7.9133(11), b = 13.0269(18), c = 19.091(3) (A), β = 101.906(2)°, V = 1925.6(5)(A)3, Z = 4, Mr = 409.36, Dc = 1.412 g/cm3, F(000) = 856,μ = 0.178 mm-1, S = 1.015, the final R =0.0381 and wR = 0.0906 for 2718 observed reflections with I ＞ 2σ(Ⅰ) and 262 variable parameters.This compound may be used as DNA-intercalator. Its cytotoxic activities were also tested in vitro on four human tumor cell lines.